Highly Enantioselective Synthesis of (S)-alpha-Alkyl-alpha,beta-diaminopropionic Acids via Asymmetric Phase-Transfer Catalytic Alkylation of 2-Phenyl-2-imidazoline-4-carboxylic Acid tert-Butyl Esters

摘要

An efficient enantioselective synthetic method for (S)-alpha-alkyl-alpha,beta-diaminopropionic acid is reported. The asymmetric phase-transfer catalytic alkylation of N(1)-Boc-2-phenyl-2-imidazoline-4-carboxylic acid tert -butyl ester in the presence of chiral quaternary ammonium catalyst gave the corresponding alkylated products (93-98% ee) which could be transformed to enantioenriched alpha-alkyl-alpha,beta-diaminopropionic acids.